Ball joints are utilized in many different applications, for example in holder arrangement for devices to be placed or mounted on a horizontal or vertical surface. The holder arrangement may comprise an attachment part and a base part that are connected through a ball joint. The ball joint may allow the attachment part to be moved by for example a rotational and/or a tilt movement.
In applications when a cable or the like is arranged through a ball joint, it is desirable to provide a rotation stop that limits the rotational movement of the attachment part relative the base part. An unlimited rotational movement of the attachment part relative the base part may cause a problem in that the cable may be twisted beyond function, be sheared off, or a continuous rotation may dislodge connectors thereof.
One way of creating a rotation stop in a ball joint is to provide a groove around the waist of the ball of the ball joint. A pin that is positioned in the ball socket of the ball joint protrudes into the groove of the ball. The groove is formed with ends so as to provide end positions for the pin when moved along the groove during rotation of the ball. Thus, the rotational movement of the ball in the ball socket is limited by the end positions.
However, by this solution the rotational movement is limited to an angle less than 360 degrees. In other words, the ball cannot be rotated in the whole rotational span. This is an undesired limitation in applications having for example a monitoring camera as part of the attachment part. In such cases, a rotation of at least 360 degrees of the ball, and thereby the attachment part, is desired.
A solution to this problem is provided by document U.S. Pat. No. 3,312,482 that discloses a rotatable swivel assembly. The assembly comprises a rotation limiting arrangement for preventing excessive twisting of an electrical extending through the swivel. A swivel member is arranged in a cup member that, in turn, is arranged in a tubular housing. A first co-acting stop means is arranged on the swivel housing and the cup member. A second co-acting stop means is arranged on the cup member and the swivel member. The co-acting stop means limit the rotation of the swivel member relative to the swivel housing while still allowing a rotation of at least 360 degrees.
It may however be desirable to provide an improved ball joint in view of its design and functions.